I had the same problem. They say, they could see the booking in booking.com, but not in their own (Marriott) system. And because of that my claim could not be verified.
This was for the CY Ginza.
HTB.
I have worked out where my problem is! So the Kayak.co.uk site has one price inc taxes - the Kayak USA price is more expensive and has taxes in addition. Marriott say they can only agree claims that they can verify... even though i have sent a screen shot and a link!
anyone have any ideas?